This invention concerns a method of operating a fuel cell, and also concerns apparatus to perform the method when in combination with the fuel cell.
The fuel cell concerned is of the type (hereinafter called the type referred to) comprising an anode and a cathode each comprising catalyst means comprising platinum.
It is known to supply fuel cells of the type referred to with hydrogen gas fuel to the anode and oxygen gas oxidant to the cathode. The hydrogen should not contain substances Which will poison the catalyst means. It is known to supply hydrogen produced by reforming a hydrocarbon, for example methane or natural gas. However the resultant hydrogen may also contain carbon monoxide which is preferentially adsorbed onto the surface of the anode catalyst means comprising platinum and poisons the catalyst means at the anode resulting in the effective internal resistance of the cell increasing and the external current decreasing to a low or possibly zero level. Thus as the anode becomes increasingly poisoned, the cell performance deteriorates. To avoid poisoning of the catalyst means, it is known to use catalytic or other means to convert the carbon monoxide in the hydrogen fuel gas to carbon dioxide (or some other substance, for example methane, which does not poison the catalyst means) before the hydrogen is supplied to the cell.
The provision of such catalytic or other means to convert carbon monoxide to carbon dioxide (or said other substance which is non-poisonous to the catalyst means) externally of the fuel cell not only adds an extra process and increases costs, but it does not cure the problem of detoxifying the catalyst means of the anode, should any carbon monoxide be carried into the cell with the hydrogen.
An object of the invention is to provide a method of operating a fuel cell of the type referred to in which the catalyst means of the anode which may be subject to poisoning by carbon monoxide can be detoxified (or the cell rejuvenated) in a relatively simple and inexpensive manner.